A wide variety of packaging materials and containers are already known, and their contents are also varied. These include for example jelly candy, pudding, yogurt, liquid detergent, toothpaste, instant curry, syrup, petroleum jelly, facial cleansing cream, facial cleansing mousse and other foods, drinks, medicines, cosmetics, chemical products and the like. The contents also come in various forms, including solids, semi-solids, liquids, viscous materials, gels and the like.
In addition to sealing performance, the packaging materials used in packaging these contents are also required to have thermal adhesive properties, light shielding properties, heat resistance, durability and other properties suited to the contents, the package type, the application and the like. However, the following problem remains even if a packaging material satisfies all of these requirements. This is that the contents adhere to the packaging material. When the contents adhere to the packaging material it is difficult to use all of the contents, resulting in waste. Effort is required if the contents adhering to the packaging material are to be collected separately so that all the contents can be used. Therefore, in addition to sealing performance and the like as discussed above, packaging materials also need to have the property of resisting adherence of the contents to the packaging material (non-adhesive properties).
A content sticking preventive lid has been proposed (Patent Document 1) wherein in a lid provided with a heat seal layer and a base material layer integrated via an adhesive layer, the heat seal layer has a thickness exceeding 10 μm and is formed of a polyolefin containing a glycerin acid ester, polyglycerin fatty acid ester, pentaerythritol fatty acid ester, polyoxypropylene-polyoxyethylene block polymer, sorbitan fatty acid ester, polyoxyethylene alkyl ether, fatty acid amide or the like having a non-adhesive effect, and an intermediate layer formed of a polyolefin is interposed between the adhesive layer and the heat seal layer.
An apparatus provided with an easily cleanable surface coating has also been disclosed (Patent Document 2) wherein in an apparatus provided with an easily cleanable surface coating having heat resistance of at least 300° C., remarkable non-adhesive properties and a thickness of 1 to 1000 nm, the surface coating contains a metal oxide network and a hydrophobic substance, the hydrophobic substance is distributed uniformly relative to the thickness of the surface coating, and the surface coating is hydrophobic with a contact angle in excess of 90° with respect to water.    Patent Document 1: Japanese Patent Application Publication No. 2002-37310    Patent Document 2: Japanese Patent Application Publication No. 2004-130785
However, the materials of Patent Documents 1 and 2 do not provide sufficient adherence prevention effects. Further improvements are still needed for practical application.